Curing agent composition for epoxy resins, epoxy resin composition and use thereof

ABSTRACT

An epoxy resin composition comprising an epoxy resin (A), a curing agent (B) and a curing accelerator (C), wherein the curing agent (B) is a phenol compound having two or more functional groups or a compound obtained by esterification of the phenol compound or a mixture of these compounds, and the curing accelerator (C) is a salt of a phosphazenium compound represented by a formula (I):  
                 
 
     (wherein R 1 s each represent a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms or an aryl or aralkyl group having 6 to 10 carbon atoms and may be all the same or different from one another; and Z −  represents a halogen anion, hydroxy anion, alkoxy anion, aryloxy anion or carboxy anion).

TECHNICAL FIELD

[0001] The present invention relates to a semiconductor device obtainedby sealing a semiconductor integrated circuit with an epoxy resin. Thepresent invention provides an epoxy resin composition which has variousphysical properties satisfactory to make the composition usable for itsapplication, e.g., low hygroscopicity and excellent melt-flowability ofthe resin composition in particular and which provides overall crackingresistance. Further, the present invention also relates to an epoxyresin composition comprising a catalyst which causes a functional groupsuch as a phenolic hydroxyl group or an ester group to react with anepoxy group quickly, and a cured product of the epoxy resin composition.

BACKGROUND ART

[0002] Heretofore, integrated circuits (IC) and large scale integratedcircuit (LSI) have been protected from malfunctions caused by dirt,dust, heat, moisture or light in an external atmosphere by sealants forprotecting them in order for the circuits to be actually used.

[0003] In recent years, the sealants have been gradually shifted fromsealing with metal materials and ceramic materials to sealing withresins, and at present, epoxy resin sealants are predominantly used.

[0004] In particular, in view of balance between costs and physicalproperties, epoxy resin compositions using a phenol resin as a curingagent are used in large quantities. The sealants using these epoxy resincompositions have problems such as improvement in mechanical propertiesas well as:

[0005] (i) suppression of crack occurrence at the time of reflowsoldering, and

[0006] (ii) improvement in electrical reliability.

[0007] Generally, the occurrence of cracks at the time of reflowsoldering in (i) is assumed to be caused by water in the resin whichexpands sharply when exposed to high temperatures at the time of reflowsoldering. Hence, means for solving the problem is largely focused oncontrol of moisture absorptivity of the resin, and mechanical strengthand adhesion of the resin to metal are also involved in the means on thewhole.

[0008] However, since a reaction between an epoxy group and a hydroxylgroup is a reaction which always produces a hydroxyl group as shown bythe following reaction formula (1), hydrophilicity becomes higher due tothe hydroxyl group, and even if a basic skeleton is renderedhydrophobic, a reduction in the moisture absorptivity as a whole islimited.

[0009] Reaction Formula (1):

[0010] (wherein A represents an epoxy residue, and B represents a phenolresidue).

[0011] As a technique for solving these problems, a technique disclosedin, for example, EP 959088 which uses a phosphine oxide derivative as acuring accelerator has been studied.

[0012] Since an epoxy resin composition using the accelerator is curedby use of the phenol resin, moisture absorptivity is almost the same asthat when triphenylphosphine or imidazole which is a commonly usedaccelerator is used. As for improvements in other physical properties,however, a significant improvement in cracking resistance is seen.

[0013] Further, its curing behavior has a significantly great merit froman industrial standpoint in that initial curing takes long time andcomplete curing takes short time.

[0014] Meanwhile, with respect to the improvement in electricalreliability in (ii), the following problems exist.

[0015] (ii)-1: As a side reaction at the time of curing, epoxyhomopolymerization occurs in some portions. As a result, hydroxyl groupsof the phenol resin become excessive, so that the composition has poormoisture resistance and electric characteristics. Further, since theepoxy homopolymerized portions and the excessive phenol resin portionsexist in addition to an essential epoxy-phenol resin network, thecomposition also has poor mechanical properties.

[0016] (ii)-2: Mainly due to corrosion of metal portions and currentleakage of a semiconductor which are caused by incorporation of freeions, halogen ions in particular, the electrical reliability isadversely affected.

[0017] Of these, the ion impurities in (ii)-2 are a problem ofpurification and purity of the epoxy resin in particular and are notintrinsic. As for the problem of (ii)1, modification of the resin and/orcontrol of the side reaction can cause the epoxy resin composition tofully exhibit physical properties inherent in the epoxy resincomposition.

[0018] These problems indicated by (ii)-1 and (ii)-2 influence atechnique to be described hereinafter.

[0019] That is, for the purpose of reducing the moisture absorptivity ofthe resin in the foregoing problem (i), a reaction between an epoxygroup and an ester group as disclosed in Japanese Patent ApplicationLaid-Open No. 53327/1987 applied by Nishikubo et al. has been proposed.

[0020] In the publication, a quaternary onium salt and a crown ethercomplex are set forth as preferable catalysts, and in a paper [AdditionReaction of Epoxy Compound with Ester and Its Application to Synthesisof Polymer, Synthetic Organic Chemistry, Vol. 49, pp. 218 to 233 (1991)]by Nishikubo et al., yields when the catalysts are used as unitreactions are specifically described. According to the paper, althoughthe highest yield is 91% which is a yield when tetrabutylammoniumchloride is used, the yields are generally low.

[0021] It is needless to say that if an ionic compound such as thequaternary onium salt and the crown ether complex remain in a resin usedas a sealant for a semiconductor integrated circuit, this means that theionic impurities described in the foregoing (ii)-1 are added as a curingaccelerator, thereby causing undesirable results such as an electricalshort circuit as well as corrosion of metal portions in contact with theimpurities, and these undesirable results and the corrosion in turncause serious defects in products.

[0022] Meanwhile, in a general addition reaction between an epoxy resinand a phenol resin, a phosphine such as trialkylphosphine ortriarylphosphine, imidazole, a tertiary amine or the like is used as acatalyst, and particularly for sealing a semiconductor, imidazole andthe phosphines are often used. When these catalysts are used in thereaction between an epoxy group and an ester group, imidazole havingreaction activity is liable to cause epoxy homopolymerization which isthe foregoing side reaction, and the problem of the foregoing (ii)-2 isremarkable. On the other hand, although the phosphines do not have theseproblems, they have slow curing speed and provide substantially no curedproduct.

[0023] Therefore, the idea of preparing a curing agent for an epoxyresin by esterifying some or all hydroxyl groups of the phenol resin asthe curing agent for the purpose of obtaining lower hygroscopicity hasheretofore not been implemented because no effective curing catalyst hasbeen available.

[0024] Under such circumstances, in recent years, a phosphazene catalystfor curing an ester group and an epoxy group effectively has beenproposed. More specifically, it has been found that the phosphine oxidederivative disclosed in the foregoing EP 959088 is effective for anepoxy-ester curing reaction. Japanese Patent Application Laid-Open No.80049/2000 discloses its production and high activity in a unit reactionbetween an epoxy group and an ester group (reaction betweenmonofunctional compounds), and Japanese Patent Application Laid-Open No.349662/1999 discloses its application to a sealant.

[0025] However, it has been found that due to hydrolytic properties ofthe phosphine oxide derivative, if a cured resin absorbs water with thederivative contained therein and is exposed to high temperatures as inreflow soldering, the derivative is decomposed easily, and electricconductivity increases significantly. That is, the phosphine oxidederivative is not suitable as a sealant in some cases.

[0026] Further, a phosphazenium compound which is a curing catalyst isalready disclosed in Japanese Patent Application Laid-Open No.77289/1998 which also discloses that the phosphazenium compound exhibitshigh activity in a unit reaction between an epoxy group and an estergroup.

[0027] In consideration of these facts, it may seem to be easy to usethe phosphazenium compound together with an epoxy resin having two ormore functional epoxy groups and a phenol resin having two or morefunctional groups or an ester derivative thereof as a thermosettingresin. However, it is generally known that a basic reaction does notnecessarily exhibit the same level of reaction activity under a reactionin a polymer.

[0028] That is, it must be considered in the case of a three-dimensionalcrosslinking curing reaction that as three-dimensional crosslinkingproceeds, skeletal steric hindrance occurs due to bondings occurring inthe vicinity of functional groups and molecules are fixed along withcuring, so that the curing reaction may not proceed easily.

[0029] When the ionic phosphazenium compound is used as a catalyst, itis conceivable that the compound may not be a favorable catalyst for asealant with respect to which control of inclusion of ionic substancesis generally strict.

[0030] Under the circumstances, in the present invention, an epoxy resincomposition suitable for use as a sealant, a cured product thereof, anda curing agent composition for the epoxy resin composition.

DISCLOSURE OF THE INVENTION

[0031] An object of the present invention is to provide a compositionfor causing a phenol resin for providing a cured epoxy resin resinhaving low hygroscopicity and excellent electric characteristics or anester derivative thereof resulting from esterification of some or allhydroxyl groups of the phenol resin with an aliphatic acyl group oraromatic acyl group to react with an epoxy resin or compoundeffectively. In particular, an object of the present invention is toprovide an epoxy resin composition for a semiconductor sealant which isexcellent in cracking resistance and electric characteristics, a curedproduct of the composition, a semiconductor device produced by use ofthe composition, and a curing agent composition for an epoxy resin.

[0032] The present inventors have found that such objects can beachieved by a specific compound comprising a stable cation and a counteranion and have completed the present invention on the basis of thisfinding.

[0033] That is, the present invention is a curing agent composition foran epoxy resin which comprises a compound as a curing agent (B) which isselected from the group consisting of the following (B1) to (B3):

[0034] (B1) a phenol compound having two or more functional groups,

[0035] (B2) a compound in which a hydroxyl group of a phenol compoundhaving two or more functional groups is esterified with an acyl group,and

[0036] (B3) a mixture of the above compounds (B1) and (B2), and a saltof a phosphazenium compound as a curing accelerator (C) which isrepresented by the following formula (I):

[0037] (wherein R¹s each represent a hydrogen atom, a linear, branchedor cyclic alkyl group having 1 to 10 carbon atoms or an aryl or aralkylgroup having 6 to 10 carbon atoms and may be all the same or differentfrom one another; and Z⁻ represents a halogen anion, hydroxy anion,alkoxy anion, aryloxy anion or carboxy anion).

[0038] Further, the present invention is an epoxy resin compositioncomprising:

[0039] (A) an epoxy resin having two or more epoxy groups in a molecule,

[0040] (B) a curing agent, and

[0041] (C) a curing accelerator,

[0042] wherein the curing agent (B) is a compound selected from thegroup consisting of the following (B1) to (B3):

[0043] (B1) a phenol compound having two or more functional groups,

[0044] (B2) a compound in which a hydroxyl group of a phenol compoundhaving two or more functional groups is esterified with an acyl group,and

[0045] (B3) a mixture of the above (B1) and (B2),

[0046] and the curing accelerator (C) is a salt of a phosphazeniumcompound which is represented by the above formula (I).

[0047] Still further, the present invention is a cured epoxy resinobtained by heat-curing the foregoing epoxy resin composition.

[0048] Still further, the present invention is a semiconductor deviceobtained by sealing a semiconductor integrated circuit by use of theforegoing epoxy resin composition.

[0049] Still further, the present invention is an epoxy resincomposition comprising:

[0050] (A) an epoxy resin having two or more epoxy groups in a molecule,

[0051] (B) a curing agent, and

[0052] (C) a curing accelerator,

[0053] wherein the curing agent (B) is a compound selected from thegroup consisting of the following (B1) to (B3):

[0054] (B1) a phenol compound having two or more functional groups,

[0055] (B2) a compound in which a hydroxyl group of a phenol compoundhaving two or more functional groups is esterified with an acyl group,and

[0056] (B3) a mixture of the above (B1) and (B2),

[0057] and the curing accelerator (C) is a salt comprising a stablecation and a counter anion.

BRIEF DESCRIPTION OF DRAWING

[0058]FIG. 1 is a graph showing the curing behavior of an epoxy resincomposition when CURELASTOMETER is used.

BEST MODE FOR CARRYING OUT THE INVENTION

[0059] In the present invention, as a curing accelerator (C), a saltcomprising a stable cation and a counter anion typified by a salt of aphosphazenium compound which is represented by the foregoing formula (1)is used, and as the curing agent (B), a compound selected from the groupconsisting of the following (B1) to (B3)is used:

[0060] (B1) a phenol compound having two or more functional groups,

[0061] (B2) a compound in which a hydroxyl group of a phenol compoundhaving two or more functional groups is esterified with an acyl group,and

[0062] (B3) a mixture of the above (B1) and (B2),

[0063] When the mixture (B3) is used, a mixing ratio of the compound(B1) and the compound (B2) is arbitrary and should be determined bydetermining desired physical properties of a cured product according totarget application and grade.

[0064] That is, hygroscopicity lowers as the number of ester groupsincreases, while adhesion to metal such as a lead frame improves as thenumber of hydroxyl groups increases, whereby mechanical strength isimproved.

[0065] In the epoxy resin composition of the present invention, when thephosphazenium compound of the formula (1) is used as the essentialaccelerator, a reaction between an epoxy group and an ester group whichhas conventionally been unable to proceed to a sufficient degree canfully proceed as a curing reaction, a problem of the side reaction ofthe foregoing problem (ii) can be solved, and a cured product which isexcellent particularly in flexibility, moisture resistance, crackingresistance and electric characteristics can be provided, as comparedwith when conventional imidazole or triphenylphosphine is used as theaccelerator.

[0066] Further, even when an unesterified phenol resin is used, heatresistance is improved and complete curing becomes fast, as comparedwith when the conventional accelerator is used.

[0067] In addition, a resin composition prepared by adding an organicand/or inorganic filler(s) (D) to the epoxy resin composition exhibitsextremely excellent performance as a sealant for a semiconductorintegrated circuit.

[0068] Meanwhile, as compared with the aforementioned prior art using aphosphine oxide derivative as a curing accelerator, electricalreliability as electrical and electronic products improves.

[0069] That is, while the phosphine oxide derivative has hydrolyticproperties as a compound and has a problem with respect to electricalreliability, the phosphazenium compound used in the present invention isstable. Thus, the difference in electrical reliability occurs.

[0070] That is, the epoxy resin composition of the present invention ispreferably an epoxy resin composition comprising:

[0071] (A) an epoxy compound or resin having two or more functionalgroups,

[0072] (B) a phenol compound or resin having two or more functionalgroups, 0 to 100 mol % of hydroxyl groups of which have been esterifiedby acyl groups, or an ester derivative thereof, and

[0073] (C) a phosphazenium compound represented by the above formula (1)as a curing accelerator as essential components.

[0074] Hereinafter, the phosphazenium compound represented by theformula (1) which is used in the present invention will be described.

[0075] In the formula (1), substituents R¹s each represent a hydrogenatom, a linear, branched or cyclic alkyl group having 1 to 10 carbonatoms or an aryl or aralkyl group having 6 to 10 carbon atoms and may beall the same or different from one another.

[0076] Illustrative examples of R¹ include a hydrogen atom; a linear,branched or cyclic alkyl group such as a methyl group, an ethyl group,an n-propyl group, an isopropyl group, an n-butyl group, an s-butylgroup, a t-butyl group, a 1-pentyl group, a 2-pentyl group, a 3-pentylgroup, a 2methyl-1-butyl group, an isopentyl group, a t-pentyl group, a3-methyl-2-butyl group, a heopentyl group, an n-hexyl group, a4-methyl-2-pentyl group, a cyclopentyl group, a cyclohexyl group, a1-heptyl group, a 3-heptyl group, a 1octyl group, a 2-octyl group, a2-ethyl-1-hexyl group, a nonyl group or a decyl group; an aryl groupsuch as a phenyl group; and an aralkyl group such as a toluyl group, abenzyl group, a 1-phenylethyl group or a 2-phenylethyl group.

[0077] Of these, an aliphatic hydrocarbon group having 1 to 6 carbonatoms such as a methyl group, an ethyl group, an n-propyl group, anisopropyl group, an n-butyl group or a cyclohexyl group is preferable,and the methyl group and the ethyl group are more preferable.

[0078] In the formula (1), Z⁻ represents a halogen anion, hydroxy anion,alkoxy anion, aryloxy anion or carboxy anion.

[0079] In addition, any anions can be used as long as they do notinhibit the effect of the present invention.

[0080] Illustrative examples of Z⁻ include a halogen anion such as afluorine anion, a chlorine anion, a bromine anion or an iodine anion; ahydroxy anion; an alkoxy anion derived from an alcohol such as methanol,ethanol, n-propanol, isopropanol, allyl alcohol, n-butanol, s-butanol,t-butanol, cyclohexanol, 2-heptanol, 1-octanol, 1-decanol oroctahydronaphthol; an aryloxy anion derived from an aromatic hydroxycompound such as phenol, cresol, xylenol, naphthol, 2-methyl-1-naphtholor 9-phenanthrol; and a carboxy anion derived from a carboxylic acidsuch as formic acid, acetic acid, propionic acid, butyric acid,isobutyric acid, caproic acid, decanecarboxylic acid, oleic acid,benzoic acid or naphthoic acid.

[0081] Of these, the hydroxy anion; an alkoxy anion derived from analcohol having 1 to 4 carbon atoms such as methanol, ethanol,n-propanol, isopropanol, n-butanol, s-butanol or t-butanol; an aryloxyanion derived from an aromatic hydroxy compound having 6 to 8 carbonatoms such as phenol or cresol; and a benzoyloxy anion derived frombenzoic acid are preferable. More preferable are the hydroxy anion, amethoxy anion, a phenoxy anion and the benzoyloxy anion. The mostpreferable is the hydroxy anion.

[0082] These phosphazenium compounds may be used solely or in admixtureof two or more.

[0083] These phosphazenium compounds can be synthesized in accordancewith a method disclosed in Japanese Patent Application Laid-Open No.77289/1998 or a similar method.

[0084] In the epoxy resin composition of the present invention, thecuring accelerator (C) is used in an amount of 0.001 to 25 wt % (0.001to 25 g/100 g), preferably 0.01 to 15 wt %, more preferably 0.1 to 8 wt%, based on 100 wt % of a resin component (total of the epoxy resin (A)and the curing agent (B)).

[0085] Further, in the epoxy resin composition of the present invention,together with the phosphazenium compound, a generally used, knownaccelerator other than the phosphazenium compound, such as imidazole,e.g., 2-methylimidazole or a phosphine, e.g., triphenylphosphine, may beused in an amount of 0.5 to 500 wt % of the phosphazenium compound. Thecharacteristics of the present invention are exhibited readily when theamount is not higher than 500 wt % (five-fold equivalent).

[0086] The phosphazenium compound has almost no deliquescent properties.Even in the following preparation of the composition, it can be handledunder a normal atmosphere as in the case of other compounds.

[0087] In the epoxy resin composition of the present invention, theepoxy resin as the component (A) is an epoxy resin having two or moreepoxy groups in a molecule. As the epoxy resin (A), a variety ofconventionally known epoxy resins can be used regardless of molecularstructure, molecular weight and the like as long as they can be cured bya variety of curing agents as will be described later.

[0088] Firstly, preferable examples of the epoxy resin (A) include anovolac epoxy resin represented by the following formula (II), aphenol-dicyclopentadiene-type epoxy resin represented by the followingformula (III), a phenol-aralkyl-resin-type epoxy resin represented bythe following formula (IV), a naphthol-aralkyl-resin-type epoxy resinrepresented by the following formula (V), abiphenol-type-epoxy-containing epoxy resin represented by the followingformula (VI) or a bisphenol-type-epoxy-containing epoxy resinrepresented by the following formula (VII):

[0089] (wherein R²s each represent a hydrogen atom, a methyl group or anethyl group, and n which is the number of recurring units represents aninteger of 0 to 50, its average being within a range of 0 to 15),

[0090] (wherein R³s each represent a hydrogen atom, a halogen atom, alinear, branched or cyclic aliphatic alkyl group having 1 to 8 carbonatoms, an alkoxy group having 1 to 10 carbon atoms or a phenyl group,and n which is the number of recurring units represents an integer of 0to 50, its average being within a range of 0 to 15),

[0091] (wherein R⁴s each represent a hydrogen atom, a halogen atom, alinear, branched or cyclic aliphatic alkyl group having 1 to 8 carbonatoms, an alkoxy group having 1 to 10 carbon atoms or a phenyl group,and n which is the number of recurring units represents an integer of 0to 50, its average being within a range of 0 to 15),

[0092] (wherein R⁵s each represent a hydrogen atom, a halogen atom, alinear, branched or cyclic aliphatic alkyl group having 1 to 8 carbonatoms, an alkoxy group having 1 to 10 carbon atoms, a phenyl group or aglycidyl ether group, and n which is the number of recurring unitsrepresents an integer of 0 to 50, its average being within a range of 0to 15),

[0093] (wherein R⁶s each represent a hydrogen atom, a methyl group or anethyl group and may be all the same or different from one another), and

[0094] (wherein R⁷s each represent a hydrogen atom, an alkyl grouphaving 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbonatoms, an aryl group having 6 to 10 carbon atoms, an aryloxy grouphaving 6 to 10 carbon atoms or halogen and may be all the same ordifferent from one another, and Y represents an alkylidene having 1 to10 carbon atoms, an alkylene having 2 to 10 carbon atoms, acycloalkylidene having 3 to 10 carbon atoms, a cycloalkylene having 3 to10 carbon atoms or a divalent group such as —O—, —CO—, —CO₂—, S—, —SO—or—SO₂—).

[0095] As the epoxy resin (A), a variety of conventionally known epoxyresins can be used. For example, an epoxy resin synthesized from avariety of novolac resins including epichlorohydrin and bisphenol, analicyclic epoxy resin or an epoxy resin incorporating a halogen atomsuch as chlorine or bromine can be used. The above epoxy resins can beused solely or in admixture of two or more.

[0096] Preferable examples thereof include dihydroxybenzenes such ascatechol, resorcin and hydroquinone, dihydroxynaphthalenes such as1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene,1,6-dihydroxynaphthalene, 2,5-dihydroxynaphthalene and2,6-dihydroxynaphthalene, epoxy resins obtained by epoxidating phenolichydroxyl groups of a phenol novolac resin represented by the followingformula (XIV):

[0097] (wherein R¹⁴s each represent a hydrogen atom, a methyl group oran ethyl group, and n which is the number of recurring units representsan integer of 0 to 50, its average being within a range of 0 to 15),

[0098] a phenol-dicyclopentadiene resin represented by the followingformula (XV):

[0099] (wherein R¹⁵s each represent a hydrogen atom, a halogen atom, alinear, branched or cyclic aliphatic alkyl group having 1 to 8 carbonatoms, an alkoxy group having 1 to 10 carbon atoms or a phenyl group,and n which is the number of recurring units represents an integer of 0to 50, its average being within a range of 0 to 15),

[0100] a phenol aralkyl resin represented by a formula (XVI):

[0101] (wherein R¹⁶s each represent a hydrogen atom, a halogen atom, alinear, branched or cyclic aliphatic alkyl group having 1 to 8 carbonatoms, an alkoxy group having 1 to 10 carbon atoms or a phenyl group,and n which is the number of recurring units represents an integer of 0to 50, its average being within a range of 0 to 15),

[0102] a naphthol aralkyl resin represented by a formula (XVII):

[0103] (wherein R¹⁷s each represent a hydrogen atom, a halogen atom, alinear, branched or cyclic aliphatic alkyl group having 1 to 8 carbonatoms, an alkoxy group having 1 to 10 carbon atoms, a phenyl group or ahydroxyl group, and n which is the number of recurring units representsan integer of 0 to 50, its average being within a range of 0 to 15),

[0104] a biphenol represented by the following formula (XVIII):

[0105] (wherein R¹⁸s each represent a hydrogen atom, a methyl group oran ethyl group and may be all the same or different from one another)and

[0106] a bisphenol represented by a formula (XIX):

[0107] (wherein R¹⁹s each represent a hydrogen atom, an alkyl grouphaving 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbonatoms, an aryl group having 6 to 10 carbon atoms, an aryloxy grouphaving 6 to 10 carbon atoms or halogen and may be all the same ordifferent from one another, and Y represents an alkylidene having 1 to10 carbon atoms, an alkylene having 2 to 10 carbon atoms, acycloalkylidene having 3 to 10 carbon atoms, a cycloalkylene having 3 to10 carbon atoms or a divalent group such as —O—, —CO—, —CO₂—, S—, —SO—or—SO2—),

[0108] epoxy resins obtained by epoxidating amino groups of aromaticpolyamines such as 4,4′-diaminophenylmethane, 4,4′-diaminodiphenylether, 4,4′-diaminodiphenyl sulfone,2,2′-bis(4,4′-diaminophenyl)propane, m-xylylenediamine, pxylylenediamineand an aralkyl aniline resin represented by the following formula (XX):

[0109] (wherein R²⁰s each represent a hydrogen atom, a halogen atom, alinear, branched or cyclic aliphatic alkyl group having 1 to 8 carbonatoms, an alkoxy group having 1 to 10 carbon atoms or a phenyl group,and n which is the number of recurring-units represents an integer of 0to 50, its average being within a range of 0 to 15), and

[0110] epoxy compounds or-resins derived from aminophenols such asm-aminophenol, p-aminophenol,2-(4-aminophenyl)-2-(4′-hydroxyphenyl)propane and4-aminophenyl-(4′-hydroxyphenyl)-methane.

[0111] More preferable of these are epoxy resins or compounds obtainedby epoxidating a phenol novolac resin, a phenol dicyclopentadiene resin,a phenol aralkyl resin, a naphthol aralkyl resin, a biphenol and abisphenol.

[0112] In the epoxy resin composition of the present invention, as thecuring agent as the component (B), anyphenolic-hydroxyl-group-containing compounds or resins 0 to 100 mol % ofthe hydroxyl groups of which have been esterified by acyl groups andester derivatives thereof can be used.

[0113] Firstly, preferable examples of the curing agent (B) include anovolac resin represented by the following formula (VIII) or an esterderivative thereof, a phenol-dicyclopentadiene resin represented by thefollowing formula (IX) or an ester derivative thereof, a phenol aralkylresin represented by the following formula (X) or an ester derivativethereof, a naphthol aralkyl resin represented by the following formula(XI) or an ester derivative thereof, a biphenol compound represented bythe following formula (XII) or an ester derivative thereof, or abisphenol compound represented by the following formula (XIII) or anester derivative thereof:

[0114] (wherein R⁸s each represent a hydrogen atom, a methyl group or anethyl group; n which is the number of recurring units represents aninteger of 0 to 50, its average being within a range of 0 to 15; and Aseach represent a hydrogen atom in the case of the compound (B1) and anaromatic acyl group in the case of the compound (B2)),

[0115] (wherein R⁹s each represent a hydrogen atom, a halogen atom, alinear, branched or cyclic aliphatic alkyl group having 1 to 8 carbonatoms, an alkoxy group having 1 to 10 carbon atoms or a phenyl group; nwhich is the number of recurring units represents an integer of 0 to 50,its average being within a range of 0 to 15; and As each represent ahydrogen atom in the case of the compound (B1) and an aromatic acylgroup in the case of the compound (B2)),

[0116] (wherein R¹⁰s each represent a hydrogen atom, a halogen atom, alinear, branched or cyclic aliphatic alkyl group having 1 to 8 carbonatoms, an alkoxy group having 1 to 10 carbon atoms or a phenyl group; nwhich is the number of recurring units represents an integer of 0 to 50,its average being within a range of 0 to 15; and As each represent ahydrogen atom in the case of the compound (B1) and an aromatic acylgroup in the case of the compound (B2)),

[0117] (wherein R¹¹s each represent a hydrogen atom, a halogen atom, alinear, branched or cyclic aliphatic alkyl group having 1 to 8 carbonatoms, an alkoxy group having 1 to 10 carbon atoms or a phenyl group; nwhich is the number of recurring units represents an integer of 0 to 50,its average being within a range of 0 to 15; and As each represent ahydrogen atom in the case of the compound (B1) and an aromatic acylgroup in the case of the compound (B2)),

[0118] (wherein R¹²s each represent a hydrogen atom, a methyl group oran ethyl group and may be all the same or different from one another;and As each represent a hydrogen atom in the case of the compound (B1)and an aromatic acyl group in the case of the compound (B2)), and

[0119] (wherein R¹³s each represent a hydrogen atom, an alkyl grouphaving 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbonatoms, an aryl group having 6 to 10 carbon atoms, an aryloxy grouphaving 6 to 10 carbon atoms or halogen and may be all the same ordifferent from one another; Y represents an alkylidene having 1 to 10carbon atoms, an alkylene having 2 to 10 carbon atoms, a cycloalkylidenehaving 3 to 10 carbon atoms, a cycloalkylene having 3 to 10 carbon atomsor a divalent group such as —O—, —CO—, —CO₂—, S—, —SO—or —SO₂—; and Aseach represent a hydrogen atom in the case of the compound (B1) and anaromatic acyl group in the case of the compound (B2)).

[0120] Particularly preferable examples of the curing agent (B) include:

[0121] a phenol novolac resin represented by the following formula(XIV):

[0122] (wherein R ¹⁴s each represent a hydrogen atom, a methyl group oran ethyl group, and n which is the number of recurring units representsan integer of 0 to 50, its average being within a range of 0 to 15),

[0123] a phenol-dicyclopentadiene resin represented by the followingformula (XV):

[0124] (wherein R¹⁵s each represent a hydrogen atom, a halogen atom, alinear, branched or cyclic aliphatic alkyl group having 1 to 8 carbonatoms, an alkoxy group having 1 to 10 carbon atoms or a phenyl group,and n which is the number of recurring units represents an integer of 0to 50, its average being within a range of 0 to 15),

[0125] a phenol aralkyl resin represented by the following formula(XVI):

[0126] (wherein R¹⁶s each represent a hydrogen atom, a halogen atom, alinear, branched or cyclic aliphatic alkyl group having 1 to 8 carbonatoms, an alkoxy group having 1 to 10 carbon atoms or a phenyl group,and n which is the number of recurring units represents an integer of 0to 50, its average being within a range of 0 to 15),

[0127] a naphthol aralkyl resin represented by the following formula(XVII):

[0128] (wherein R¹⁷s each represent a hydrogen atom, a halogen atom, alinear, branched or cyclic aliphatic alkyl group having 1 to 8 carbonatoms, an alkoxy group having 1 to 10 carbon atoms, a phenyl group or ahydroxyl group, and n which is the number of recurring units representsan integer of 0 to 50, its average being within a range of 0 to 15),

[0129] a biphenol represented by the following formula (XVIII):

[0130] (wherein R¹⁸s each represent a hydrogen atom, a methyl group oran ethyl group and may be all the same or different from one another),and

[0131] a bisphenol represented by the following formula (XIX):

[0132] (wherein R¹⁹s each represent a hydrogen atom, an alkyl grouphaving 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbonatoms, an aryl group having 6 to 10 carbon atoms, an aryloxy grouphaving 6 to 10 carbon atoms or halogen and may be all the same ordifferent from one another, and Y represents an alkylidene having 1 to10 carbon atoms, an alkylene having 2 to 10 carbon atoms, acycloalkylidene having 3 to 10 carbon atoms, a cycloalkylene having 3 to10 carbon atoms or a divalent group such as —O—, —CO—, —CO₂—, S—, —SO—or—SO₂—).

[0133] Esterification of these phenol resins can be performed inaccordance with a known method. Further, an esterifying agent used toesterify the above hydroxyl groups may be any of an organic carboxylicanhydride, an organic carboxylic halide and an organic carboxylic acid.A convenient esterifying agent may be selected according tocharacteristics of an esterifying agent based on the number of carbonatoms of an ester desired to be derived.

[0134] Specific examples of the esterifying agent include aceticanhydride, acetyl chloride, acetyl bromide, acetic acid, propionicanhydride, propionyl chloride, propionyl bromide, propionic acid,butyric anhydride, butyric chloride, butyric acid, valeric anhydride,valeric chloride, valeric bromide, valeric acid, pivalic chloride,pivalic acid, phenylacetic acid, phenyl acetyl chloride,2-phenylpropionic acid, 3-phenylpropionic acid, o-tolylacetic acid,m-tolylacetic acid, p-tolylacetic acid, cumenic acid, benzoic anhydride,benzoic chloride, benzoic bromide, benzoic acid, o-methylbenzoicchloride, m-methylbenzoic chloride, p-methylbenzoic chloride,o-methylbenzoic acid, m-methylbenzoic acid, p-methylbenzoic acid,dimethylbenzoic acid, and naphthoic acid.

[0135] These esterifying agents can be used solely or in admixture oftwo or more.

[0136] Further, in the present invention, the rate of esterification is0 to 100 mol %, preferably 10 to 100 mol %, more preferably 50 to 100mol %, much more preferably 80 to 100 mol %, most preferably 90 to 100mol %.

[0137] In this regard, an esterification rate of 0% simply implies aphenol compound or a phenol resin.

[0138] In the epoxy resin composition of the present invention, a phenolcompound or phenol resin or an ester derivative thereof is used as thecuring agent for an epoxy resin having two or more functional groups.Since the epoxy resin composition of the present invention is intendedfor use as a thermosetting resin in the same applications as aconventional epoxy-phenol cured product is used, such a combination ofthe constituents that the composition can take a three-dimensionalstructure after cured is desirable.

[0139] As for the mixing ratio of the epoxy resin (A) and the curingagent (B), a total of hydroxyl groups and ester groups, that is, activegroups, is 0.5 to 1.5 mole equivalents, preferably 0.7 to 1.3 moleequivalents, based on 1 mole equivalent of epoxy groups. In actual use,it is more preferable to adjust and use a molar ratio with which optimumphysical properties of a cured product can be obtained.

[0140] To prepare the epoxy resin composition of the present invention,any techniques may be used. For example, it is possible that thephosphazenium compound of the formula (1) as the accelerator ismelt-mixed into the curing agent sufficiently in advance and the mixtureis then mixed with the epoxy resin or these may be mixed togethersimultaneously.

[0141] Further, to fully homogenize these materials, they may bedry-blended in powdery form.

[0142] In the epoxy resin composition of the present invention, asrequired, an organic and/or inorganic filler(s) as a component (D) andother additives may be added to the epoxy resin composition.

[0143] Particularly, when the epoxy resin composition of the presentinvention is used as a sealant for a semiconductor integrated circuit,it is desirable to use the organic and/or inorganic filler(s) (D) and avariety of additives such as a colorant, e.g. carbon black, a moldreleasing agent, a coupling agent and a flame retardant for the purposesof improving its mechanical properties and reducing an overall cost.

[0144] The amount of the organic and/or inorganic filler(s) (D) ispreferably 100 parts by weight to 1,900 parts by weight based on 100parts by weight of a total of the epoxy resin (A) and the curing agent(B). From the viewpoints of moisture resistance and mechanical strength,the amount is more preferably not smaller than 250 parts by weight,particularly preferably not smaller 550 parts by weight.

[0145] Illustrative examples of the organic and/or inorganic filler(s)(D) include powders such as silica, alumina, silicon nitride, siliconcarbide, talc, calcium silicate, calcium carbonate, mica, clay andtitanium white, and fibers such as glass fibers, carbon fibers andaramid fibers. Of these, crystalline silica and/or fused silica are/ispreferably used in the sealant. Further, in consideration of flowabilityof the resin composition at the time of molding, the silicas desirablyhave spherical shapes or a combination of spherical shapes and irregularshapes.

[0146] Further, in the epoxy resin composition of the present invention,in consideration of mechanical strength and heat resistance, it isdesirable to use a coupling agent to improve adhesion between the resinand the filler. Illustrative examples of the coupling agent include asilane coupling agent, a titanate coupling agent, an aluminate couplingagent and a zircoaluminate coupling agent. Of these, the silane couplingagent is preferable, and particularly, a silane coupling agent having afunctional group which reacts with an epoxy group is the mostpreferable.

[0147] Specific examples of such a coupling agent include vinyltrimethoxysilane, vinyl triethoxysilane,N-(2-amino-methyl)-3-aminopropylmethyldimethoxysilane,N-(2-amino-ethyl)-3-aminopropyltrimethoxysilane,3-aminopropyltriethoxysilane, 3-anilinopropyltriethoxysilane,3-glycidoxy-propyltrimethoxysilane,3-glycidoxypropylmethyldimethoxysilane,2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,3-methacryloxypropyltrimethoxysilane, and3-mercaptopropyltrimethoxysilane. These can be used solely or incombination of two or more.

[0148] It is desirable that these coupling agents be adsorbed to thesurface of the filler or solidified by a reaction in advance.

[0149] As a method for producing a semiconductor device by sealing asemiconductor integrated circuit by use of the epoxy resin compositionof the present invention, low pressure transfer molding can be said tobe the most commonly used. However, other methods such as injectionmolding, compression molding and cast molding can also be used, and aspecial technique using a solvent can also be used.

[0150] Hereinafter, the present invention will be described in detailwith reference to Examples. However, the present invention shall not belimited by the Examples in any way.

SYNTHETIC EXAMPLE 1

[0151] To a glass container equipped with a thermometer, an agitator, adropping funnel and a reflux condenser, 312 g (3 mol) of phenol novolacresin (trade name: BRG#558, product of SHOWA HIGHPOLYMER, hydroxyl groupequivalent: 104 g/eq) was added, and the internal temperature of thecontainer was raised to 125° C. With the internal temperature kept atthe above temperature, 336.9 g (3.3 mol) of acetic anhydride was addeddropwise in two hours under agitation. Thereafter, with the internaltemperature kept at 125° C., the reaction was carried out for 2 hours,and then the temperature was raised to 140° C. At 140 to 150° C., themixture was aged for 2 hours, and then excessive acetic anhydride andby-produced acetic acid were distilled off under a reduced pressure at150° C./10 mmHg at the highest.

[0152] The obtained resin was dissolved in 1,400 g of toluene and thenwashed with hot water at 60 to 70° C. until waste water becomes neutral,and toluene was distilled off at 150° C./5 mmHg at the highest so as toobtain 370 g of phenol novolac resin having completely acetylatedhydroxyl groups. Its hydroxyl group equivalent was not smaller than3,000 g/eq (undetectable).

SYNTHESIS EXAMPLE 2

[0153] To a glass container equipped with a thermometer, an agitator, adropping funnel and a reflux condenser, 312 g (3 mol) of phenol novolacresin (trade name: BRG#558, product of SHOWA HIGHPOLYMER, hydroxyl groupequivalent: 104 g/eq) was added, and the internal temperature of thecontainer was raised to 125° C. With the internal temperature kept atthe above temperature, 421.7 g (3 mol) of benzoyl chloride was addeddropwise in two hours under agitation. A hydrogen chloride gas producedduring the reaction was absorbed into a trap. Thereafter, with theinternal temperature kept at 125° C., the reaction was carried out for 2hours, and then the temperature was raised to 140° C. At 140 to 150° C.,the mixture was aged for 2 hours, and then hydrochloric acid was removedunder a slightly reduced pressure.

[0154] The obtained resin was dissolved in 1,400 g of toluene and thenwashed with hot water at 60 to 70° C. until waste water becomes neutral,and toluene was distilled off at 150° C./5 mmHg at the highest so as toobtain 590 g of phenol novolac resin having completely benzoylatedhydroxyl groups. Its hydroxyl group equivalent was not smaller than3,000 g/eq (undetectable).

SYNTHETIC EXAMPLE 3

[0155] To a glass container equipped with a thermometer, an agitator, adropping funnel and a reflux condenser, 507 g (3 mol) of phenol aralkylresin (trade name: MIREX XLC-4L, hydroxyl group equivalent: 169 g/eq,product of Mitsui Chemicals, Inc.) was added, and the internaltemperature of the container was raised to 125° C. With the internaltemperature kept at the above temperature, 336.9 g (3.3 mol) of aceticanhydride was added dropwise in two hours under agitation. Thereafter,with the internal temperature kept at 125° C., the reaction was carriedout for 2 hours, and then the temperature was raised to 140° C. At 140to 150° C., the mixture was aged for 2 hours, and then excessive aceticanhydride and by-produced acetic acid were distilled off under a reducedpressure at 150° C./10 mmHg at the highest.

[0156] The obtained resin was dissolved in 1,400 g of toluene and thenwashed with hot water at 60 to 70° C. until waste water becomes neutral,and toluene was distilled off at 150° C./5 mmHg at the highest so as toobtain 609 g of phenol aralkyl resin having completely acetylatedhydroxyl groups. Its hydroxyl group equivalent was not smaller than3,000 g/eq (undetectable).

SYNTHESIS EXAMPLE 4

[0157] To a glass container equipped with a thermometer, an agitator, adropping funnel and a reflux condenser, 507 g (3 mol) of phenol aralkylresin (trade name: MIREX XLC-4L, hydroxyl group equivalent: 169 g/eq,product of Mitsui Chemicals, Inc.) was added, and the internaltemperature of the container was raised to 125° C. With the internaltemperature kept at the above temperature, 421.7 g (3 mol) of benzoylchloride was added dropwise in two hours under agitation. A hydrogenchloride gas produced during the reaction was absorbed into a trap.Thereafter, with the internal temperature kept at 125° C., the reactionwas carried out for 2 hours, and then the temperature was raised to 140°C. At 140 to 150° C., the mixture was aged for 2 hours, and thenhydrochloric acid was removed under a slightly reduced pressure.

[0158] The obtained resin was dissolved in 1,400 g of toluene and thenwashed with hot water at 60 to 70° C. until waste water becomes neutral,and toluene was distilled off at 150° C./5 mmHg at the highest so as toobtain 785 g of phenol aralkyl resin having completely benzoylatedhydroxyl groups. Its hydroxyl group equivalent was not smaller than3,000 g/eq (undetectable).

SYNTHETIC EXAMPLE 5

[0159] To a glass container equipped with a thermometer, an agitator, adropping funnel and a reflux condenser, 540 g (3 mol) ofphenol-dicyclopentadiene resin (trade name: DPR-5000, product of MitsuiChemicals, Inc., hydroxyl group equivalent: 180 g/eq) was added, and theinternal temperature of the container was raised to 125° C. With theinternal temperature kept at the above temperature, 336.9 g (3.3 mol) ofacetic anhydride was added dropwise in two hours under agitation.Thereafter, with the internal temperature kept at 125° C., the reactionwas carried out for 2 hours, and then the temperature was raised to 140°C. At 140 to 150° C., the mixture was aged for 2 hours, and thenexcessive acetic anhydride and by-produced acetic acid were distilledoff under a reduced pressure at 150° C./10 mmHg at the highest.

[0160] The obtained resin was dissolved in 1,400 g of toluene and thenwashed with hot water at 60 to 70° C. until waste water becomes neutral,and toluene was distilled off at 150° C./5 mmHg at the highest so as toobtain 610 g of phenol-dicyclopentadiene-resin-type resin havingcompletely acetylated hydroxyl groups. Its hydroxyl group equivalent wasnot smaller than 3,000 g/eq (undetectable).

SYNTHESIS EXAMPLE 6

[0161] To a glass container equipped with a thermometer, an agitator, adropping funnel and a reflux condenser, 540 g (3 mol) ofphenol-dicyclopentadiene resin (trade name: DPR-5000, product of MitsuiChemicals, Inc., hydroxyl group equivalent: 180 g/eq) was added, and theinternal temperature of the container was raised to 125° C. With theinternal temperature kept at the above temperature, 421.7 g (3 mol) ofbenzoyl chloride was added dropwise in two hours under agitation. Ahydrogen chloride gas produced during the reaction was absorbed into atrap. Thereafter, with the internal temperature kept at 125° C., thereaction was carried out for 2 hours, and then the temperature wasraised to 140° C. At 140 to 150° C., the mixture was aged for 2 hours,and then hydrochloric acid was removed under a slightly reducedpressure.

[0162] The obtained resin was dissolved in 1,400 g of toluene and thenwashed with hot water at 60 to 70° C. until waste water becomes neutral,and toluene was distilled off at 150° C./5 mmHg at the highest so as toobtain 810 g of phenol-dicyclopentadiene-resin-type resin havingcompletely benzoylated hydroxyl groups. Its hydroxyl group equivalentwas not smaller than 3,000 g/eq (undetectable). SYNTHETIC EXAMPLE 7

[0163] To a glass container equipped with a thermometer, an agitator, adropping funnel and a reflux condenser, 654 g (3 mol) of naphtholaralkyl resin (trade name: α-NX-3.2, product of Mitsui Chemicals, Inc.,hydroxyl group equivalent: 218 g/eq) was added, and the internaltemperature of the container was raised to 125° C. With the internaltemperature kept at the above temperature, 336.9 g (3.3 mol) of aceticanhydride was added dropwise in two hours under agitation. Thereafter,with the internal temperature kept at 125° C., the reaction was carriedout for 2 hours, and then the temperature was raised to 140° C. At 140to 150° C., the mixture was aged for 2 hours, and then excessive aceticanhydride and by-produced acetic acid were distilled off under a reducedpressure at 150° C./10 mmHg at the highest.

[0164] The obtained resin was dissolved in 1,400 g of toluene and thenwashed with hot water at 60 to 70° C. until waste water becomes neutral,and toluene was distilled off at 150° C./5 mmHg at the highest so as toobtain 745 g of naphthol aralkyl resin having completely acetylatedhydroxyl groups. Its hydroxyl group equivalent was not smaller than3,000 g/eq (undetectable).

SYNTHESIS EXAMPLE 8

[0165] To a glass container equipped with a thermometer, an agitator, adropping funnel and a reflux condenser, 654 g (3 mol) of naphtholaralkyl resin (trade name: α-NX-3.2, product of Mitsui Chemicals, Inc.,hydroxyl group equivalent: 218 g/eq) was added, and the internaltemperature of the container was raised to 125° C. With the internaltemperature kept at the above temperature, 421.7 g (3 mol) of benzoylchloride was added dropwise in two hours under agitation. A hydrogenchloride gas produced during the reaction was absorbed into a trap.Thereafter, with the internal temperature kept at 125° C., the reactionwas carried out for 2 hours, and then the temperature was raised to 140°C. At 140 to 150° C., the mixture was aged for 2 hours, and thenhydrochloric acid was removed under a slightly reduced pressure.

[0166] The obtained resin was dissolved in 1,400 g of toluene and thenwashed with hot water at 60 to 70° C. until waste water becomes neutral,and toluene was distilled off at 150° C./5 mmHg at the highest so as toobtain 923 g of naphthol aralkyl resin having completely benzoylatedhydroxyl groups. Its hydroxyl group equivalent was not smaller than3,000 g/eq (undetectable).

SYNTHESIS EXAMPLE 9

[0167] 588 g of phenol novolac resin having 88% of its hydroxyl groupsbenzoylated was obtained in the same manner as in Synthesis Example 2except that the amount of benzoyl chloride was changed to 371.2 g (2.64mol). Its hydroxyl group equivalent was 958 g/eq.

EXAMPLE 1

[0168] 1 gram equivalent of o-cresol novolac (trade name: EOCN102S-65,product of NIPPON KAYAKU CO., LTD., epoxy equivalent: 210 g/eq) as anepoxy resin and 1 gram equivalent of the acetylated phenol novolac resin(ester equivalent: 146 g/eq=calculated value) of Synthesis Example 1 asa curing agent were fully melt-mixed with each other at 100° C. so as toobtain a homogeneous resin mixture.

[0169] To the resin mixture, 0.0055 mol of phosphazenium compound of theforegoing formula (1) wherein R¹ was a methyl group was added as acuring accelerator, and the resulting mixture was mixed at 120° C. for 1minute so as to obtain a resin composition.

[0170] To 200 g of the resin composition, a filler and other additiveswere added in the following amounts, and the mixture was roll-mixedunder heating so as to obtain a molding material for a sealant:

[0171] Inorganic Filler [Spherical Fused Silica (YXK-35R, product ofTATSUMORI CO., LTD.)]: 1,440 g

[0172] Silane Coupling Agent (SZ-6083, product of Dow Corning ToraySilicone Co., Ltd.): 124 g

[0173] Carnauba Wax: 90 g

[0174] Carbon Black: 6 g

[0175] Antimony Oxide: 20 g

[0176] Using a portion of the molding material, a cured product wasobtained under conditions of 175° C./10 min and 150 kg/cm² and thenafter-cured at 175° C./8 hr (nitrogen atmosphere) so as to fully curethe product. Physical properties were measured by use of the curedproduct.

[0177] Further, by use of the same molding material, test semiconductordevices were prepared by low pressure transfer molding, and a crackingtest was conducted by means of a solder bath.

EXAMPLE 2

[0178] Tests were conducted in the same manner as in Example 1 exceptthat the curing agent was changed to the benzoylated phenol novolacresin of Synthesis Example 2.

EXAMPLE 3

[0179] Tests were conducted in the same manner as in Example 1 exceptthat the epoxy compound was changed to YX4000H, the curing agent waschanged to the acetylated phenol aralkyl resin of Synthesis Example 3,and a composition was obtained by a method comprising the steps of fullymelt-mixing the curing agent with the accelerator at 120° C. in advanceand then adding the epoxy resin.

EXAMPLE 4

[0180] Tests were conducted in the same manner as in Example 3 exceptthat the curing agent was changed to the benzoylated phenol aralkylresin of Synthesis Example 4.

EXAMPLE 5

[0181] Tests were conducted in the same manner as in Example 1 exceptthat the curing agent was changed to the acetylatedphenol-dicyclopentadiene resin of Synthesis Example 5.

EXAMPLE 6

[0182] Tests were conducted in the same manner as in Example 1 exceptthat the curing agent was changed to the benzoylatedphenol-dicyclopentadiene resin of Synthesis Example 6.

EXAMPLE 7

[0183] Tests were conducted in the same manner as in Example 3 exceptthat the curing agent was changed to the acetylated naphthol aralkylresin of Synthesis Example 7.

EXAMPLE 8

[0184] Tests were conducted in the same manner as in Example 3 exceptthat the curing agent was changed to the benzoylated naphthol aralkylresin of Synthesis Example 8.

COMPARATIVE EXAMPLE 1

[0185] A resin composition was prepared in the same manner as in Example1 except that the accelerator was changed to 0.015 mol oftriphenylphosphine. However, a cured product was not obtained. Further,although gelation time was also measured at 150° C. and 200° C. for 20minutes, the test was stopped since no gelation was seen.

COMPARATIVE EXAMPLE 2

[0186] A resin composition was prepared in the same manner as in Example2 except that the accelerator was changed to 0.015 mol oftriphenylphosphine. However, a cured product was not obtained. Further,although gelation time was also measured at ₁₅₀° C. and 200° C. for 20minutes, the test was stopped since no gelation was seen.

COMPARATIVE EXAMPLE 3

[0187] Tests were conducted in the same manner as in Comparative Example1 except that the curing agent was changed to a phenol novolac resin(trade name: BRG#558, product of SHOWA HIGHPOLYMER, hydroxyl groupequivalent: 104 g/eq).

COMPARATIVE EXAMPLE 4

[0188] Tests were conducted in the same manner as in Comparative Example1 except that the curing agent was changed to aphenol-dicyclopentadiene-resin-type resin (trade name: DPR-5000, productof Mitsui Chemicals, Inc., hydroxyl group equivalent: 180 g/eq).

COMPARATIVE EXAMPLE 5

[0189] Tests were conducted in the same manner as in Example 3 exceptthat the accelerator was changed to 0.015 mol of triphenylphosphine andthe curing agent was changed to a phenol aralkyl resin (trade name:MIREX XLC-4L, hydroxyl group equivalent: 169 g/eq, product of MitsuiChemicals, Inc.).

EXAMPLE 9

[0190] Tests were conducted in the same manner as in Example 3 exceptthat the curing agent was changed to the phenol novolac resin ofSynthesis Example 9 having 88% of its hydroxyl groups benzoylated.

EXAMPLE 10

[0191] Tests were conducted in the same manner as in Example 3 exceptthat the curing agent was changed to a mixture of the benzoylated phenolnovolac resin of Synthesis Example 2 and a phenol novolac resin (tradename: BRG#558, product of SHOWA HIGHPOLYMER, hydroxyl group equivalent:104 g/eq) at a mixing ratio of 88:12 (ratio of functional groups).

COMPARATIVE EXAMPLE 6

[0192] A resin composition was prepared in the same manner as in Example9 except that the accelerator was changed to 0.015 mol oftriphenylphosphine. However, a cured product was not obtained.

COMPARATIVE EXAMPLE 7

[0193] A resin composition was prepared in the same manner as in Example10 except that the accelerator was changed to 0.015 mol oftriphenylphosphine. However, a cured product was not obtained.

Evaluation Results

[0194] The results of the foregoing Examples and Comparative Examplesare shown in Tables 1 to 4. Gelation times of the resin compositionsprior to the roll mixing were measured at 150° C. Further, physicalproperties were measured in accordance with the following testingmethods.

[0195] Tg (Glass Transition Temperature): This was measured inaccordance with a TMA needle penetration method (Shimadzu TMA-DRWDT-30).

[0196] Post-Boiling Water Absorption: An increase in weight after boiledin boiling water of 100° C. for 2 hours was measured.

[0197] V.P.S Test: Test semiconductor devices were molded and left tostand in a bath kept at a constant temperature of 85° C. and a constanthumidity of 85% for 168 hours. Immediately after that, the devices wereput in a Fluorinert™ liquid (product of Sumitomo 3M, FC-70) of 240° C.The number of semiconductors whose package resins were cracked wascounted. The test value was expressed in the form of a fraction, with anumerator representing the number of cracked semiconductors and n=5.TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Glass Transition Temperature 153148 108 99 129 (° C.) Post-Boiling Water Absorption 0.09 0.16 0.09 0.080.08 (%) V.P.S Test (Rate of Occurrence 0 0 0 0 0 of Cracks (%))Gelation Time (min′ sec″) 4′41″ 5′25″ 5′22″ 5′52″ 4′59″

[0198] TABLE 2 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Glass TransitionTemperature 119 111 105 116 116 (° C.) Post-Boiling Water Absorption0.10 0.11 0.06 0.10 0.10 (%) V.P.S Test (Rate of Occurrence 0 0 0 0 0 ofCracks (%)) Gelation Time (min′ sec″) 5′56″ 5′42″ 5′30″ 5′35″ 5′31″

[0199] TABLE 3 Comp. Comp. Comp. Comp. Comp. Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex.5 Glass Transition — — 173 141 100 Temperature (° C.) Post-Boiling Water— — 0.21 0.15 0.12 Absorption (%) V.P.S Test (Rate of — — 3 2 1Occurrence of Cracks (%)) Gelation Time Not Not 3′38″ 4′41″ 4.37″ (min′sec″) Cured Cured

[0200] TABLE 4 Comp. Comp. Ex. 6 Ex. 7 Glass Transition Temperature (°C.) — — Post-Boiling Water Absorption (%) — — V.P.S Test (Rate ofOccurrence of Cracks (%)) — — Gelation Time (min′ sec″) Not Not CuredCured

[0201] With reference to the foregoing Examples, curing of theesterified phenol resins and the epoxy resins has been described indetail. An epoxy resin composition containing the accelerator andphosphazenium compound of the present invention as essential componentsand a compound whose hydroxyl groups have been esterified by acyl groupsas a curing agent has far superior hygroscopicity and is veryadvantageous in terms of cracking resistance as compared with aconventional epoxy resin/phenol resin cured product. It is therebyunderstood that the epoxy resin compound is excellent in crackingresistance as a sealant.

[0202] Further, it is realized that when triphenylphosphine (TPP) whichis a conventional accelerator is used, triphenylphosphine does not causea curing reaction in portions esterified by acryl groups, as shown byComparative Examples 1 and 2. From this fact, it is understood that theesterified curing agent and the phosphazenium compound are essentialcomponents so as to obtain high physical properties as the sealant inthe present invention.

EXAMPLE 11

[0203] 1 gram equivalent of o-cresol novolac (trade name: EOCN102S-65,product of NIPPON KAYAKU CO., LTD., epoxy equivalent: 210 g/eq) as anepoxy resin and 1 gram equivalent of phenol novolac resin (trade name:BRG#558, product of SHOWA HIGHPOLYMER, hydroxyl group equivalent: 104g/eq) as a curing agent were fully melt-mixed with each other at 100° C.so as to obtain a homogeneous resin mixture.

[0204] To the resin mixture, 0.0055 mol of phosphazenium compound of theforegoing formula (1) wherein all Rs were a methyl group and Z⁻ was ahydroxy anion was added as a curing accelerator, and the resultingmixture was mixed at 80° C. for 1 minute so as to obtain a resincomposition.

[0205] To 200 g of the resin composition, a filler and other additiveswere added in the following amounts, and the mixture was roll-mixedunder heating so as to obtain a molding material for a sealant:

[0206] Inorganic Filler [Spherical Fused Silica (YXK-35R, product ofTATSUMORI CO., LTD.)]: 1,440 g

[0207] Silane Coupling Agent (SZ-6083, product of Dow Corning ToraySilicone Co., Ltd.): 124 g

[0208] Carnauba Wax: 90 g

[0209] Carbon Black: 6 g

[0210] Antimony Oxide: 20 g

[0211] Using a portion of the molding material, a cured product wasobtained under conditions of 150° C.→185° C./5 min, 185° C./5 min and150 kg/cm² and then after-cured at 185° C./8 hr (nitrogen atmosphere) soas to fully cure the product. Tests were conducted with respect tocuring behavior and the like.

EXAMPLE 12

[0212] Tests were conducted in the same manner as in Example 11 exceptthat the curing agent was changed to a phenol-dicyclopentadiene resin(trade name: DPR-5000, product of Mitsui Chemicals, Inc., hydroxyl groupequivalent: 180 g/eq).

EXAMPLE 13

[0213] Tests were conducted in the same manner as in Example 12 exceptthat the epoxy resin was changed to tetramethylbiphenoldiglycidyl ether(trade name: YX4000H, product of JER CO., LTD., epoxy equivalent: 184g/eq).

EXAMPLE 14

[0214] Tests were conducted in the same manner as in Example 13 exceptthat the curing agent was changed to a naphthol aralkyl resin (tradename: α-NX-3.2, product of Mitsui Chemicals, Inc., hydroxyl groupequivalent: 218 g/eq).

EXAMPLE 15

[0215] Tests were conducted in the same manner as in Example 14 exceptthat the curing agent was changed to a phenol aralkyl resin (trade name:MIREX XLC-4L, hydroxyl group equivalent: 169 g/eq, product of MitsuiChemicals, Inc.).

EXAMPLE 16

[0216] Tests were conducted in the same manner as in Example 11 exceptthat the epoxy resin was changed to aphenol-dicyclopentadiene-resin-type epoxy resin (trade name: EPICHRONHP-7200, product of DAINIPPON INK AND CHEMICALS, INC., epoxy equivalent:262 g/eq).

EXAMPLE 17

[0217] Tests were conducted in the same manner as in Example 16 exceptthat the curing agent was changed to a phenol aralkyl resin (trade name:MIREX XLC-4L, hydroxyl group equivalent: 169 g/eq, product of MitsuiChemicals, Inc.).

EXAMPLE 18

[0218] Tests were conducted in the same manner as in Example 17 exceptthat the epoxy resin was changed to a phenol-aralkyl-resin-type epoxyresin: MIREX XLC-4L (product of Mitsui Chemicals, Inc., hydroxyl groupequivalent: 169 g/eq) epoxidated in accordance with a conventionalmethod.

EXAMPLE 19

[0219] Tests were conducted in the same manner as in Example 11 exceptthat the epoxy resin was changed to a dihydroxynaphthalenediglycidylether (trade name: EPICHRON HP4032, product of DAINIPPON INK ANDCHEMICALS, INC., 150 g/eq).

EXAMPLE 20

[0220] Tests were conducted in the same manner as in Example 19 exceptthat the epoxy resin was changed to bisphenol-A-type diglycidyl ether(trade name: EPICOAT 828, product of JER CO., LTD., epoxy equivalent:184 g/eq).

COMPARATIVE EXAMPLE 8

[0221] Tests were conducted in the same manner as in Example 11 exceptthat the accelerator was changed to 0.008 mol of triphenylphosphine(TPP).

COMPARATIVE EXAMPLE 9

[0222] Tests were conducted in the same manner as in Example 12 exceptthat the accelerator was changed to 0.008 mol of triphenylphosphine(TPP).

COMPARATIVE EXAMPLE 10

[0223] Tests were conducted in the same manner as in Example 13 exceptthat the accelerator was changed to 0.015 mol of triphenylphosphine(TPP).

COMPARATIVE EXAMPLE 11

[0224] Tests were conducted in the same manner as in Example 14 exceptthat the accelerator was changed to 0.015 mol of triphenylphosphine(TPP).

COMPARATIVE EXAMPLE 12

[0225] Tests were conducted in the same manner as in Example 15 exceptthat the accelerator was changed to 0.015 mol of triphenylphosphine(TPP).

COMPARATIVE EXAMPLE 13

[0226] Tests were conducted in the same manner as in Example 16 exceptthat the accelerator was changed to 0.008 mol of triphenylphosphine(TPP).

COMPARATIVE EXAMPLE 14

[0227] Tests were conducted in the same manner as in Example 17 exceptthat the accelerator was changed to 0.008 mol of triphenylphosphine(TPP).

COMPARATIVE EXAMPLE 15

[0228] Tests were conducted in the same manner as in Example 18 exceptthat the accelerator was changed to 0.008 mol of triphenylphosphine(TPP).

COMPARATIVE EXAMPLE 16

[0229] Tests were conducted in the same manner as in Example 19 exceptthat the accelerator was changed to 0.008 mol of triphenylphosphine(TPP).

COMPARATIVE EXAMPLE 17

[0230] Tests were conducted in the same manner as in Example 20 exceptthat the accelerator was changed to 0.015 mol of triphenylphosphine(TPP).

COMPARATIVE EXAMPLE 18

[0231] Tests were conducted in the same manner as in Example 11 exceptthat the accelerator was changed to 0.008 mol of 2-undecylimidazole.

COMPARATIVE EXAMPLE 19

[0232] Tests were conducted in the same manner as in Example 12 exceptthat the accelerator was changed to 0.008 mol of 2-undecylimidazole.

COMPARATIVE EXAMPLE 20

[0233] Tests were conducted in the same manner as in Example 13 exceptthat the accelerator was changed to 0.015 mol of 2-methylimidazole.

COMPARATIVE EXAMPLE 21

[0234] Tests were conducted in the same manner as in Example 14 exceptthat the accelerator was changed to 0.015 mol of 2-methylimidazole.

COMPARATIVE EXAMPLE 22

[0235] Tests were conducted in the same manner as in Example 15 exceptthat the accelerator was changed to 0.015 mol of 2-methylimidazole.

COMPARATIVE EXAMPLE 23

[0236] Tests were conducted in the same manner as in Example 16 exceptthat the accelerator was changed to 0.008 mol of 2-undecylimidazole.

COMPARATIVE EXAMPLE 24

[0237] Tests were conducted in the same manner as in Example 17 exceptthat the accelerator was changed to 0.008 mol of 2-undecylimidazole.

COMPARATIVE EXAMPLE 25

[0238] Tests were conducted in the same manner as in Example 18 exceptthat the accelerator was changed to 0.008 mol of 2-undecylimidazole.

COMPARATIVE EXAMPLE 26

[0239] Tests were conducted in the same manner as in Example 19 exceptthat the accelerator was changed to 0.008 mol of 2-undecylimidazole.

Evaluation Results

[0240] The results of the foregoing Examples and Comparative Examplesare shown in Tables 5 to 10. A method for testing curing behavior is asfollows. Further, FIG. 1 is a graph showing the curing behavior of anepoxy resin composition when CURELASTOMETER is used.

[0241] Curing Behavior: This was measured by CURELASTOMETER V modelmanufactured by NSC.

[0242] Mold: P-200 Temperature: 175° C. (fluctuated)

[0243] Frequency: 100 cycle/min Amplitude Angle: ±1°

[0244] Amount of Sample: 4.5 g TABLE 5 Ex. 11 EX. 12 Ex. 13 Ex. 14 Ex.15 Glass Transition 179 147 138 135 119 Temperature (° C.) FlexuralStrength 14.9 13.5 12 12.5 12.3 (Kgf/mm2) Flexural Elastic Modulus 15001540 1670 1610 1650 (Kgf/mm2) Post-Boiling Water 0.16 0.09 0.08 0.110.09 Absorption (%) V.P.S Test 0 0 0 0 0 (Number of Cracks/10) GelationTime 3′01″ 3′31″ 5′12″ 5′02″ 5′13″ (min′ sec″) Torque Start tsx 10″ 19″1′05″ 1′12″ 1′10″ (min′ sec″) 10% Cured t′ c 19″ 34″ 1′24″ 1′41″ 1′31″(min′ sec″) 90% Cured t′ c 2′21″ 3′15″ 2′58″ 3′17″ 3′07″ (min′ sec″)

[0245] TABLE 6 EX. 16 EX. 17 Ex. 18 EX. 19 Ex. 20 Glass Transition 158129 131 146 140 Temperature (° C.) Flexural Strength 13.8 13.5 13 13.612.2 (Kgf/mm2) Flexural Elastic Modulus 1460 1590 1620 1530 1630(Kgf/mm2) Post-Boiling Water 0.14 0.11 0.12 0.14 0.13 Absorption (%)V.P.S Test 0 0 0 0 0 (Number of Cracks/10) Gelation Time 3′28″ 3′18″3′31″ 3′20″ 5′22″ (min′ sec″) Torque Start tsx 09″ 11″ 13″ 09″ 1′35″(min′ sec″) 10% Cured t′ c 22″ 23″ 25″ 21″ 2′07″ (min′ sec″) 90% Curedt′ c 2′55″ 2′45″ 2′37″ 2′35″ 4′57″ (min′ sec″)

[0246] TABLE 7 Comp. Comp. Comp. Comp. Comp. EX. 8 Ex. 9 Ex. 10 Ex. 11Ex. 12 Glass Transition 175 145 106 115 102 Temperature (° C.) FlexuralStrength 13.9 13.5 12.2 12.4 13 (Kgf/mm2) Flexural Elastic Modulus 15001500 1550 1540 1540 (Kgf/mm2) Post-Boiling Water 0.22 0.15 0.1 0.1 0.09Absorption (%) V.P.S Test 2 2 1 1 1 (Number of Cracks/10) Gelation Time5′08″ 6′55″ 4′23″ 4′28″ 4′39″ (min′ sec″) Torque Start tsx 18″ 35″ 29″28″ 29″ (min′ sec″) 10% Cured t′ c 23″ 43″ 41″ 39″ 39″ (min′ sec″) 90%Cured t′ c 5′48″ 9′22″ 9′29″ 7′21″ 6′58″ (min′ sec″)

[0247] TABLE 8 Comp. Comp. Comp. Comp. Comp. Ex. 13 Ex. 14 Ex. 15 Ex. 16Ex. 17 Glass Transition 152 126 129 147 138 Temperature (° C.) FlexuralStrength 12.8 12.8 12.6 12.7 12.3 (Kgf/mm2) Flexural Elastic Modulus1440 1550 1460 1515 1550 (Kgf/mm2) Post-Boiling Water 0.21 0.17 0.180.22 0.13 Absorption (%) V.P.S Test 2 2 2 2 1 (Number of Cracks/10)Gelation Time 5′13″ 6′31″ 6′12″ 5′45″ 4′33″ (min′ sec″) Torque Start tsx17″ 21″ 21″ 29″ 29″ (min′ sec″) 10% Cured t′ c 29″ 31″ 30″ 41″ 41″ (min′sec″) 90% Cured t′ c 5′55″ 6′22″ 16′21″ 6′09″ 6′29″ (min′ sec″)

[0248] TABLE 9 Comp. Comp. Comp. Comp. Comp. Ex. 18 Ex. 19 Ex. 20 Ex. 21Ex. 22 Glass Transition 175 144 107 116 104 Temperature (° C.) FlexuralStrength 14.1 13.5 12.3 12.4 12.6 (Kgf/mm2) Flexural Elastic Modulus1480 1510 1550 1530 1510 (Kgf/mm2) Post-Boiling Water 0.21 0.15 0.1 0.090.12 Absorption (%) V.P.S Test 2 2 1 1 1 (Number of Cracks/10) GelationTime 4′25″ 5′22″ 4′37″ 4′45″ 4′41″ (min′ sec″) Torque Start tsx 27″ 38″30″ 26″ (min′ sec″) 23″ 10% Cured t′ c 30″ 40″ 59″ 52″ 51″ 90% Cured t′c 5′13″ 6′18″ 9′45″ 7′11″ 6′45″ (min′ sec″)

[0249] TABLE 10 Comp. Comp. Comp. Comp. Ex. 23 Ex. 24 Ex. 25 Ex. 26Glass Transition Temperature 151 125 127 146 (° C.) Flexural Strength(Kgf/mm2) 12.9 12.8 12.3 13.7 Flexural Elastic Modulus 1410 1470 14901540 (Kgf/mm2) Post-Boiling Water Absorption 0.2 0.15 0.16 0.2 (%) V.P.STest 2 2 1 2 (Number of Cracks/10) Gelation Time (min′ sec″) 4′52″ 5′19″5′22″ 4′55″ Torque Start tsx (min′ sec″) 22″ 25″ 25″ 25″ 10% Cured t′ c(min′ sec″) 33″ 34″ 36″ 35″ 90% Cured t′ c (min′ sec″) 5′25″ 5′31″ 5′18″5′54″

EXAMPLE 21

[0250] 0.05 g of phosphazene compound of the formula 1 wherein all R1swere a methyl group was dissolved in 100 g of pure water and then boiledat 950° C. for 20 hours and then at 125° C. for 20 hours (in a glassautoclave). Thereafter, conductivity of the water was measured.

COMPARATIVE EXAMPLE 25

[0251] Conductivity was measured in the same manner by use of 0.05 g oftris[tris(dimethylamino)phospholanilidene-amino]phosphine oxide in placeof the phosphazene compound of Example 18.

[0252] The results of the foregoing Example and Comparative Example areshown in Table 11. TABLE 11 Ex. 21 Comp. Ex. 25 Processing Temperature95° C. 125° C. 95° C. 125° C. Conductivity (μs/cm) 100 104 94 413

[0253] As is understood from these conductivities, while the essentialphosphazene catalyst in the present invention shows constantconductivity regardless of the processing temperature, thereby inferringit from analogy that the catalyst is stable, the phosphine oxidecompound of the Comparative Example shows that conductivity became overfour times larger as the temperature increased from 95° C. to 125° C.That is, it is assumed that at high temperatures, it produces aconductive material of some type by decomposition. Therefore, it hasbeen found that they have a large difference with respect to electriccharacteristics as a sealant.

[0254] Further, as has already been described with reference toExamples, it is understood that when a phosphazene compound which is anessential accelerator in the present invention is used in a case where aphenol resin is used as a curing agent, improvements in physicalproperties such as an increase in Tg and lowered moisture absorptivitycan be recognized and, what is more, distinctive curing properties canalso be seen, as compared with when conventionally used general-purposetriphenylphosphine is used.

[0255] That is, the gelation time is significantly reduced, and the timerequired for 90% curing in measurement of an increase in torque alongwith curing by use of the CURELASTOMETER is significantly reduced. Thisleads to a reduction in cost along with a shortened production cycle inindustrial production of a sealant and makes a great contribution froman industrial standpoint.

Industrial Applicability

[0256] As described above, the epoxy resin composition obtained by thepresent invention can be used in industrial fields in which theconventional epoxy resin composition has been used. Particularly, whenused as a sealant for a semiconductor, it provides a package with bettercracking resistance than the conventional epoxy resin/phenol resin curedproduct does.

1. A curing agent composition for an epoxy resin, comprising a compoundas a curing agent (B) which is selected from the group consisting of thefollowing (B1) to (b3): (B1) a phenol compound having two or morefunctional groups, (B2) a compound in which a hydroxyl group of a phenolcompound having two or more functional groups is esterified with an acylgroup, and (B3) a mixture of the compounds (B1) and (B2), and a salt ofa phosphazenium compound as a curing accelerator (C) which isrepresented by the following formula (I):

(wherein R¹s each represent a hydrogen atom, a linear, branched orcyclic alkyl group having 1 to 10 carbon atoms or an aryl or aralkylgroup having 6 to 10 carbon atoms and may be all the same or differentfrom one another; and Z⁻ represents a halogen anion, hydroxy anion,alkoxy anion, aryloxy anion or carboxy anion).
 2. The composition ofclaim 1, wherein R¹s in the formula (1) are each a methyl group or anethyl group.
 3. The composition of claim 1, wherein Z⁻ in the formula(1) is a hydroxy anion.
 4. The composition of claim 1, wherein thecuring agent (B) is a novolac resin represented by the following formula(VIII) or an ester derivative thereof, a phenoldicyclopentadiene resinrepresented by the following formula (IX) or an ester derivativethereof, a phenol aralkyl resin represented by the following formula (X)or an ester derivative thereof, a naphthol aralkyl resin represented bythe following formula (XI) or an ester derivative thereof, a biphenolcompound represented by the following formula (XII) or an esterderivative thereof, or a bisphenol compound represented by the followingformula (XIII) or an ester derivative thereof:

(wherein R⁸s each represent a hydrogen atom, a methyl group or an ethylgroup; n which is the number of recurring units represents an integer of0 to 50, its average being within a range of 0 to 15; and As eachrepresent a hydrogen atom in the case of the compound (B1) and anaromatic acyl group in the case of the compound (B2)),

(wherein R⁹s each represent a hydrogen atom, a halogen atom, a linear,branched or cyclic aliphatic alkyl group having 1 to 8 carbon atoms, analkoxy group having 1 to 10 carbon atoms or a phenyl group; n which isthe number of recurring units represents an integer of 0 to 50, itsaverage being within a range of 0 to 15; and As each represent ahydrogen atom in the case of the compound (B1) and an aromatic acylgroup in the case of the compound (B2)),

(wherein R¹⁰s each represent a hydrogen atom, a halogen atom, a linear,branched or cyclic aliphatic alkyl group having 1 to 8 carbon atoms, analkoxy group having 1 to 10 carbon atoms or a phenyl group; n which isthe number of recurring units represents an integer of 0 to 50, itsaverage being within a range of 0 to 15; and As each represent ahydrogen atom in the case of the compound (B1) and an aromatic acylgroup in the case of the compound (B2)),

(wherein R¹¹s each represent a hydrogen atom, a halogen atom, a linear,branched or cyclic aliphatic alkyl group having 1 to 8 carbon atoms, analkoxy group having 1 to 10 carbon atoms or a phenyl group; n which isthe number of recurring units represents an integer of 0 to 50, itsaverage being within a range of 0 to 15; and As each represent ahydrogen atom in the case of the compound (B1) and an aromatic acylgroup in the case of the compound (B2)),

(wherein R¹²s each represent a hydrogen atom, a methyl group or an ethylgroup and may be all the same or different from one another; and As eachrepresent a hydrogen atom in the case of the compound (B1) and anaromatic acyl group in the case of the compound (B2)), and

(wherein R¹³ s each represent a hydrogen atom, an alkyl group having 1to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, anaryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10carbon atoms or halogen and may be all the same or different from oneanother; Y represents an alkylidene having 1 to 10 carbon atoms, analkylene having 2 to 10 carbon atoms, a cycloalkylidene having 3 to 10carbon atoms, a cycloalkylene having 3 to 10 carbon atoms or a divalentgroup such as —O—, —CO—, —CO₂—, —S—, —SO—or —SO₂—; and As each representa hydrogen atom in the case of the compound (B1) and an aromatic acylgroup in the case of the compound (B2)).
 5. An epoxy resin compositioncomprising: (A) an epoxy resin having two or more epoxy groups in amolecule, (B) a curing agent, and (C) a curing accelerator, wherein thecuring agent (B) is a compound selected from the group consisting of thefollowing (B1) to (B3): (B1) a phenol compound having two or morefunctional groups, (B2) a compound in which a hydroxyl group of a phenolcompound having two or more functional groups is esterified with an acylgroup, and (B3) a mixture of the (B1) and (B2), and the curingaccelerator (C) is a salt of a phosphazenium compound which isrepresented by the following formula (I):

(wherein R¹s each represent a hydrogen atom, a linear, branched orcyclic alkyl group having 1 to 10 carbon atoms or an aryl or aralkylgroup having 6 to 10 carbon atoms and may be all the same or differentfrom one another; and Z⁻ represents a halogen anion, hydroxy anion,alkoxy anion, aryloxy anion or carboxy anion).
 6. The composition ofclaim 5, wherein R¹s in the formula (1) each represent a methyl group oran ethyl group.
 7. The composition of claim 5, wherein Z⁻ in the formula(1) represents a hydroxy anion.
 8. The composition of claim 5, whereinthe epoxy resin (A) having two or more epoxy groups in a molecule is anovolac epoxy resin represented by the following formula (II), aphenol-dicyclopentadiene epoxy resin represented by the followingformula (III), a phenol-aralkyl-resin-type epoxy resin represented bythe following formula (IV), a naphthol-aralkyl-resin-type epoxy resinrepresented by the following formula (V), abiphenol-type-epoxy-containing epoxy resin represented by the followingformula (VI) or a bisphenol-type-epoxy-containing epoxy resinrepresented by the following formula (VII):

(wherein R²s each represent a hydrogen atom, a methyl group or an ethylgroup, and n which is the number of recurring units represents aninteger of 0 to 50, its average being within a range of 0 to 15),

(wherein R³s each represent a hydrogen atom, a halogen atom, a linear,branched or cyclic aliphatic alkyl group having 1 to 8 carbon atoms, analkoxy group having 1 to 10 carbon atoms or a phenyl group, and n whichis the number of recurring units represents an integer of 0 to 50, itsaverage being within a range of 0 to 15),

(wherein R⁴s each represent a hydrogen atom, a halogen atom, a linear,branched or cyclic aliphatic alkyl group having 1 to 8 carbon atoms, analkoxy group having 1 to 10 carbon atoms or a phenyl group, and n whichis the number of recurring units represents an integer of 0 to 50, itsaverage being within a range of 0 to 15),

(wherein R⁵s each represent a hydrogen atom, a halogen atom, a linear,branched or cyclic aliphatic alkyl group having 1 to 8 carbon atoms, analkoxy group having 1 to 10 carbon atoms, a phenyl group or a glycidylether group, and n which is the number of recurring units represents aninteger of 0 to 50, its average being within a range of 0 to 15),

(wherein R⁶s each represent a hydrogen atom, a methyl group or an ethylgroup and may be all the same or different from one another), and

(wherein R⁷s each represent a hydrogen atom, an alkyl group having 1 to10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, an arylgroup having 6 to 10 carbon atoms, an aryloxy group having 6 to 10carbon atoms or halogen and may be all the same or different from oneanother, and Y represents an alkylidene having 1 to 10 carbon atoms, analkylene having 2 to 10 carbon atoms, a cycloalkylidene having 3 to 10carbon atoms, a cycloalkylene having 3 to 10 carbon atoms or a divalentgroup such as —O—, —CO—, —CO₂—, —S—, —SO—or —SO2—).
 9. The compositionof claim 5, wherein the curing agent (B) is a novolac resin representedby the following formula (VIII) or an ester derivative thereof, aphenoldicyclopentadiene resin represented by the following formula (IX)or an ester derivative thereof, a phenol aralkyl resin represented bythe following formula (X) or an ester derivative thereof, a naphtholaralkyl resin represented by the following formula (XI) or an esterderivative thereof, a biphenol compound represented by the followingformula (XII) or an ester derivative thereof, or a bisphenol compoundrepresented by the following formula (XIII) or an ester derivativethereof:

(wherein R⁸s each represent a hydrogen atom, a methyl group or an ethylgroup; n which is the number of recurring units represents an integer of0 to 50, its average being within a range of 0 to 15; and As eachrepresent a hydrogen atom in the case of the compound (B1) and anaromatic acyl group in the case of the compound (B2)),

(wherein R⁹s each represent a hydrogen atom, a halogen atom, a linear,branched or cyclic aliphatic alkyl group having 1 to 8 carbon atoms, analkoxy group having 1 to 10 carbon atoms or a phenyl group; n which isthe number of recurring units represents an integer of 0 to 50, itsaverage being within a range of 0 to 15; and As each represent ahydrogen atom in the case of the compound (B1) and an aromatic acylgroup in the case of the compound (B2)),

(wherein R¹⁰s each represent a hydrogen atom, a halogen atom, a linear,branched or cyclic aliphatic alkyl group having 1 to 8 carbon atoms, analkoxy group having 1 to 10 carbon atoms or a phenyl group; n which isthe number of recurring units represents an integer of 0 to 50, itsaverage being within a range of 0 to 15; and As each represent ahydrogen atom in the case of the compound (B1) and an aromatic acylgroup in the case of the compound (B2)),

(wherein R¹¹s each represent a hydrogen atom, a halogen atom, a linear,branched or cyclic aliphatic alkyl group having 1 to 8 carbon atoms, analkoxy group having 1 to 10 carbon atoms or a phenyl group; n which isthe number of recurring units represents an integer of 0 to 50, itsaverage being within a range of 0 to 15; and As each represent ahydrogen atom in the case of the compound (B1) and an aromatic acylgroup in the case of the compound (B2)),

(wherein R s each represent a hydrogen atom, a methyl group or an ethylgroup and may be all the same or different from one another; and As eachrepresent a hydrogen atom in the case of the compound (B1) and anaromatic acyl group in the case of the compound (B2)), and

(wherein R¹³s each represent a hydrogen atom, an alkyl group having 1 to10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, an arylgroup having 6 to 10 carbon atoms, an aryloxy group having 6 to 10carbon atoms or halogen and may be all the same or different from oneanother; Y represents an alkylidene having 1 to 10 carbon atoms, analkylene having 2 to 10 carbon atoms, a cycloalkylidene having 3 to 10carbon atoms, a cycloalkylene having 3 to 10 carbon atoms or a divalentgroup such as —O—, —CO—, —CO₂—, —S—, —SO—or —SO₂—; and As each representa hydrogen atom in the case of the compound (B1) and an aromatic acylgroup in the case of the compound (B2)).
 10. The composition of claim 5,containing an organic and/or inorganic filler(s) (D) in an amount of 100to 1,900 parts by weight based on 100 parts by weight of a total of theepoxy resin (A) having two or more epoxy groups in a molecule and thecuring agent (B).
 11. A cured epoxy resin obtained by heat-curing theepoxy resin composition of claim
 5. 12. A semiconductor device obtainedby sealing a semiconductor integrated circuit by use of the epoxy resincomposition of claim
 5. 13. An epoxy resin composition comprising: (A)an epoxy resin having two or more epoxy groups in a molecule, (B) acuring agent, and (C) a curing accelerator, wherein the curing agent (B)is a compound selected from the group consisting of the following (B1)to (B3): (B1) a phenol compound having two or more functional groups,(B2) a compound in which a hydroxyl group of a phenol compound havingtwo or more functional groups is esterified with an acyl group, and (B3)a mixture of the above (B1) and (B2), and the curing accelerator (C) isa salt comprising a stable cation and a counter anion.